"Based on what was analyzed until now, what we understand is that (North Korea) launched many 240mm, 300mm multiple rocket launchers including new model of tactical guided weapons and assess that the range is about 70-240km," the South Korean military said in a statement, using the same terminology as the North for the new ballistic missile fired during the drill.

The exercise was reportedly conducted to "increase the combat ability" of the North Korean forces. Kim instructed service members to maintain a high alert posture.

300mm Multiple Rocket Launcher (MRL) KCNA via REUTERS

The launch and subsequent release of photos of what appear to be short-range ballistic missiles, what some are calling North Korea's version of the Russian Iskander missile, is the first clear indication that "Rocket Man" is back in the missile testing business.

It's been over a year since Kim launched a ballistic missile, the last of which was the Hwasong-15 intercontinental ballistic missile tested in late November 2017.

Unidentified short-range ballistic missile KCNA via Reuters

This show of force is perceived as a signal to the Trump administration, a message that Pyongyang's patience is running out.

"This is largely a warning to Trump that he could lose the talks unless Washington takes partial denuclearization steps offered by Kim," Shin Beom-chul, a senior fellow at the Asan Institute for Policy Studies, told Reuters. "A resumption of long-range test could be next unless Kim gets what he wants soon."

North Korea's leader Kim Jong Un supervises a "strike drill" for multiple launchers and tactical guided weapon into the East Sea during a military drill in North Korea KCNA via REUTERS

The exercise comes after several rounds of failed negotiations, including two leadership summits attended by Kim and President Donald Trump.

Trump's response was surprisingly measured. "Anything in this very interesting world is possible," he tweeted Saturday, adding that Kim "knows that I am with him & does not want to break his promise to me." The president then insisted that a "deal will happen."